function Dictionary(){
	let Items = {};
	this.has = (key) => {
		return key in Items;
	}
	this.set = (key,value) => {
		Items[key] = value
	}

	this.delete = (key) => {
		if(!this.has(key)) {
			delete Items[key]
			return true;
		}
		return false;
	}
	this.get = (key) => {
		return this.has(key) ? Items[key] : undefined;
	}
	this.values = () => {
		return Object.values(Items)
	}
	this.clear = () => {
		Items = {}
	}
	this.size = () => {
		return this.values().length
	}
	this.keys = () => {
		return Object.keys(Items)
	}
	this.getItems = () => {
		return Items
	}
}

let a = new Dictionary();
a.set('a','c')
a.set('f','d')
console.log(a.keys())